This R21, exploratory application will apply insights gained from studies of unilateral neglect to the investigation and treatment of dsyphagia. The long term goal is to establish a pharmacological treatment for both disorders that can be applied during the subacute stage of stroke when neglect and dysphagia are most problematic for rehabilitation. The specific aims are to investigate how perception of stimulus intensity (magnitude estimation) is altered by hypoarousal and how an alteration of magnitude estimation accounts for aspects of neglect and dysphagia. A final specific aim is to determine whether a pharmacological agent approved to treat sleep disorders (modafinil, Provigil) can be used to improve arousal-related deficits in neglect and dsyphagia. This research is significant and it can have a direct and immediate impact on public health. Both neglect and dysphagia are common, disabling conditions associated with stroke that affect up to 300,000 patients annually in the United States. Both disorders impede rehabilitation and they place patients at increased risk for additional injury and hospitalization due either to falls or aspiration pneumonia, respectively. There is no widely effective form of pharmacological treatment for either disorder. We plan to test our aims by measuring arousal, magnitude estimation, neglect and dysphagia in unilateral stroke patients both before and after caloric stimulation;shown to temporarily increase arousal and improve neglect. We will also examine, using a placebo-controlled study design with treatment-reversal, whether temporary improvement can identify patients who respond chronically to modafinil (Provigil) therapy. This research can produce breakthrough discoveries both for understanding swallowing impairment in dysphagia and for the management of literally thousands of stroke patients in the US who suffer from neglect and dysphagia during rehabilitation therapy. PUBLIC HEALTH RELEVANCE: Project Narrative This proposal aims to improve public health in the US by establishing a pharmacological treatment standard for neglect and dysphagia that could be made available to stroke patients immediately. Stroke affects 600,000 patients annually in the United States. Between 20 and 45% of stroke patients have either neglect, dysphagia or both disorders. Neglect is a leading predictor of poor rehabilitation outcome and a major cause of additional injury due to falls. Dysphagia can lead to respiratory complications, aspiration pneumonia, and even death. There is no widely effective pharmacological treatment for either disorder at the present time.